Field of Disclosure
The following relates generally to wireless communication, and more specifically to flexible multiplexing operation for downlink (DL) data and hybrid automatic repeat request (HARM) feedback for variable transmission time interval (TTI), including variable TTIs for enhanced component carriers (eCC).
Description of Related Art
Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems, (e.g., a Long Term Evolution (LTE) system).
By way of example, a wireless multiple-access communications system may include a number of base stations, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UEs). A base station may communicate with the communication devices on downlink channels (e.g., for transmissions from a base station to a UE) and uplink channels (e.g., for transmissions from a UE to a base station).
Some wireless systems may employ time division duplexing (TDD), in which the same frequency resources are used for UL and DL transmissions. In such systems, a multiplexing mode may be selected to serve multiple UEs. For example, a base station may choose to switch to UL after transmitting data to a single UE, after transmitting to multiple UEs one after the other, or after transmitting to multiple UEs that are allocated different frequency ranges. However, each method may result in a different tradeoffs between latency, resource efficiency, and scheduling flexibility.
Increasingly, many wireless applications benefit from reduced latency communication. Additionally, wide bandwidth carriers and spectrum sharing (e.g., unlicensed spectrum use) have introduced more flexibility, and a greater number of variables for efficient system operation, including issues related to efficient feedback to maintain low latency.